The present invention relates to the general field of transformers. In particular, the invention relates to a three-phase/two-phase transformer.
In certain situations, it may be necessary to transfer energy or signals in balanced manner from a three-phase source to a two-phase source. There exist three-phase/two-phase transformers that are stationary, and in particular one known as a “Scott connection” and another known as a “Leblanc connection”.
FIG. 1 is a diagram of the Scott connection. Two single-phase transformers 1 and 2 are used. The transformer 1 has a primary 3 with n1 turns and a secondary 6 with n2 turns. The transformer 2 has a primary 4 with n′1 turns and a secondary 7 with n2 turns.
In FIG. 1, there can be seen:                A, B, and C, which are the points for connection to the three-phase network;        Ia, Ib, and Ic, which are the three-phase currents entering via the points A, B, and C; and        V1, I1, V2, I2, which are the two-phase voltages and currents.        
The transformer 1 has its n1-turn primary 3 connected between the terminals A and B of the three-phase network. The transformer 2 has its n′1-turn primary 4 connected between the terminal C of the three-phase network and the midpoint 5 of the primary 3 of the transformer 1.
The primary voltages are in quadrature, as are the secondary voltages V1 and V2.
For a ratio n′1=(√3/2)n1, the secondary voltages V1 and V2 have the same value and they are in quadrature. The ratio of the currents is given by:
            I      c              I      2        =            2              3              ⁢                  n        2                    n        1            
When it is desired to transfer energy or signals in balanced manner from a three-phase source to a two-phase source in reference frames that are rotating relative to each other, one solution consists in using a stationary three-phase/two-phase transformer and two single-phase rotary transformers. Another solution consists in using three single-phase rotary transformers in a Leblanc connection.
Nevertheless, both of those solutions require considerable weight and volume. Furthermore, the first solution encounters current inrush problems when switching on and also problems of residual magnetization.
There thus exists a need for an improved solution that enables energy to be transferred in balanced manner from a three-phase source to a two-phase source in reference frames that are rotating relative to each other.